Urothelial carcinomas (UCs), also known as transitional cell carcinomas, account for the majority of upper urinary tract tumors. The gold-standard therapy for operable patients with localized disease is radical nephroureterectomy. However, some patients are not surgical candidates. Data on the use of modern radiation therapy for upper urinary tract UC (UTUC) are scarce. The purpose of this study was to assess the safety and efficacy of SABR in UTUC.

This retrospective study included all patients with UTUC treated with SABR at one institution. Charts were reviewed to evaluate renal function and the development of toxicity using Common Terminology Criteria for Adverse Events, version 3.0. Tumor response on follow-up imaging with computed tomography or magnetic resonance imaging scans was assessed using the Response Evaluation Criteria in Solid Tumors, version 1.1.

A total of 16 patients (7 patients with UC at the ureter and 9 at the renal pelvis) were identified as treated with SABR. Of the 9 patients with renal pelvis UC, 4 had a previous history of bladder cancer. At the time of treatment, the median age was 85 years (range, 67-95 years). Most patients received 40 Gy in 8 fractions every second day. The median followup was 21 months (range, 3-110 months). Most patients maintained stable renal function, and only 2 patients developed worsening chronic kidney disease, but none required dialysis. Acutely, 4 patients developed grade 1 diarrhea, and 1 patient had new grade 1 hematuria. No chronic side effects were observed. One patient did not have follow-up imaging and was excluded from the tumor-response analysis. Two patients had a complete response of the treated lesion, 9 had a partial response, 2 had stable disease, and 2 had disease progression within the treatment field.

This small case series suggests that SABR for UTUC is safe and well-tolerated, with good radiographic tumor response to ablative doses of radiation therapy.